Turbine speed control system

ABSTRACT

In the speed control mechanism of this invention, the piston rod of a fluid operated Servo motor is connected to the steam supply valve. The turbine governor is directly connected to the pilot control valve of the Servo motor by a linkage assembly, a portion of which is connected to the piston rod and functions upon operation of the pilot control valve by the governor to return the valve to normal position when the turbine speed has been returned to the set point.

United States Patent Czuszak 1 Nov. 21, 1972 [54] TURBINE SPEED CONTROL SYSTEM 2,646,812 7/1953 Rheingans et a]. ..4l5/43 72 Inventor: Charles C. Czuszak, GreenSburg 3,152,601 10/1964 Kremkoff ..415/43 3,332,431 7/1967 Lmder ..4l5/43 [73] Assignee: Carrier Corporation, Syracuse, N.Y. primary c Husar 22 Filed; Mal-ch 10 971 Attrney-Harry G. Martin, Jr. and J. Raymond Curti 21] App]. No.: 122,846

'[57 ABSTRACT [52] U.S. Cl. ..4l/36, 415/40, 415/43 In the Speed comm] mechanism of this invention the lift. pi of a operated Servo motor is [58] Field of Search ..415/36, 40, 43 nected to the steam Supp)! valve The turbine gown nor is directly connected to the pilot control valve of [56] Raferences and the Servo motor by a linkage assembly, a portion of UNITED STATES PATENTS which is connected to the piston rod and functions upon operation of the pilot control valve by the gover- R13,229 4/ 1911 Samuelson ..4l5/40 not to return the valve to normal position when the 1,807,173 5/1931 Ray ..415/43 turbine speed has been returned to the set point 1,966,225 7/1934 Standerwick ..415/43 1,976,659 /1934 Dickinson ..4l5/43 1 Claim, 7 Drawing Figures PATENTED I97? 3. 703, 339

SHEET 1 OF 2 ATTORNEY PATENTEDuum I972 SHEET 2 OF 2 FIG.3

. 23 FIGS INVENTOR.

CHARLES c. c USZAK ATTORNEY TURBINE SPEED CONTROL SYSTEM BACKGROUND OF THE INVENTION Turbine speed control systems have included arrangements wherein the pilot valve of a Servo motor is directly connected to the governor mechanism and is which the valving is repositioned to null upon the turbine speed being re-established at the set point. However in such systems, the valving is reset by shifting the valve porting which involves a complicated and costly structure.

This invention has as an object, a speed control mechanism for turbines and the like embodying a particular compact, simple structural arrangement, the components of which may be manufactured and assembled at low cost.

SUMMARY OF THE INVENTION The structural arrangement of the invention is such that in the preferred embodiment it can be mounted on the frame of the Servo motor, exteriorly of the cylinder thereof, and the motor can be attached directly to the turbine steam valve or steam chest. The governor is connected to the pilot valve of the Servo motor by a linkage system, all the components of which are formed of flat bar stock. A link is connected to the pilot valve and at its opposite end there is a pivotal connection, the position of which is determined by the position of the Servo piston rod. The governor is connected to this link intermediate its ends and effects movement of the link and accordingly the pilot valve about the pivot, the position of which is determined by the position of the Servo piston rod. Upon actuation of the link, and therefore the pilot valve, by the governor, the resultant movement of the piston rod repositions the pivot about which the link is moved by the governor, effecting a repositioning or return of the actuated valve to the null position when the turbine speed is re-established to the set point.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of the fluid supply valve structure and Servo motor mechanism, and including the turbine governor shown in elevation.

FIG. 2 is an enlarged top plan view of the Servo motor and linkage assembly, the view being taken on a line corresponding to line 2-2, FIG. 1.

FIG. 3 is an enlarged view of the structure shown at the left portion of FIG. 1 with the Servo pilot valve in the null or normal position.

FIG. 4 is a view similar to FIG. 3 in which the pilot valve has been moved by the governor upon reduction of turbine speed from the set point.

FIG. 5 is a view similar to FIG. 4 in which the pilot valve has been returned to normal position upon movement by the Servo motor of the supply valve to the new position.

FIG. 6 is a sectional view taken on line 6-6, FIG. 3.

FIG. 7 is a view taken on line 7-7, FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the fluid supply or steam valve for the turbine is formed with a body 10, having an inlet 11 and an outlet 12. A seat member 13 is positioned in the body 10. The seat 13 is of cylindrical form and is provided, on its inner surface, with valve element engaging surfaces 14 and with openings 15 intermediate the surfaces 14.

A spider member 20 is affixed to one end of the seat member 13, and is formed with a central aperture to slidably receive an extension 21 of the Servo motor piston rod 23. The valve is provided with a closure member 25, affixed to the valve body 10 as by cap screws 26. The closure 25 is also apertured to slidably receive the rod 21 and is formed with a packing gland 27 and gland nut 28. A valve element 30 of annular form is provided with webs 31 extending radially from a hub 33 fixedly secured to the rod 21. The valve is formed with surfaces 35 spaced apart complemental to the spacing of the seat areas 14 for movement into and out of engagement therewith, upon reciprocation of the rod 21. In FIG. 1, the valve element 30 is shown at midstroke at which position there is a flow of steam from the inlet 11 through and around the valve 30 to the outlet port 12. V

The Servo motor structure consists of a discoidal portion 37 attached to the closure 25 as by screws 38. Side members 40, 41, extend outwardly from the portion 37 and support a cylinder 43. The side member 40 is formed with an upwardly extending flange 45, the upper edge of which merges with the top surface of the cylinder 43. The inner end of the cylinder is closed by a wall 47. A piston 48 is slidably mounted in the cylinder bore 49 and is fixed to the piston rod 23.

The turbine governor 50 is mounted on a supporting bracket 51 which may be attached to the valve body 10 or the turbine proper. The governor 50 may be of any conventional type driven by the turbine, such as a fly ball governor. The centrifugal force produced by the governor being effective to produce oscillation of the output shaft 53 to which there is fixedly secured the arm 55.

A rock shaft 57 is joumaled for oscillation in the sleeve 60, shown in section in FIG. 2, fixedly secured in the side wall 45, and an offset arm 61 is fixed to one end of the rock shaft 57. An adjustable coupling 63 is pivotally connected to the free end of the arm 61 and is attached to a link 65 by a threaded connection 67 for adjustment axially of the link 65. The opposite end of the link 65 is provided with a similar coupling 68 pivotally connected to the free end of the arm 55.

A drive lever 70 is fixedly secured at one end of the inner end of the rock shaft 57 as by set screw 71. The opposite end of the lever 70 is connected to one end of a connecting link by pivot pin 76. The opposite end of the link 75 is connected to a link 77 intennediate the ends thereof by pivot pin 78. One end of link 77 is pivotally connected to the extending end portion of pivot valve 80 as by pin 81. The opposite end of the link 77 is pivotally connected to one end of a repositioning link 83 by pivot pin 85. The opposite end of the link 83 is pivotally connected to a repositioning lever 87 intermediate the ends thereof. One end of the lever 87 is mounted for oscillation about a pivot pin 88 fixed in the side wall 45. As shown in FIGS. 6 and 7, the lower end of the lever 87 is bifurcated for engagement with a pin 90 carried in a bifurcated block 91 fixed to the piston rod 23 as by set screw 93.

The cylinder 43 is formed with radial passages 95, 96, communicating with the ends of the cylinder bore 49 and with a valve passage 97. The cylinder structure is also formed with a inlet port 98 and exhaust ports 100, 101. Referring to FIG. 3, the valve 80 is shown in normal or null position with the center land 103 covering the inlet port 98, the land 105 covering the exhaust port 100, and the land 106 formed by the outwardly extending portion of the valve 80 covering the exhaust port 101. It will be noted, the pivot pins 78, 81 and 85 are in vertical alignment as indicated by the dash line 110. Also the pins 88, 90 are in the vertical plane shown by dash line 112.

It is now assumed that with an increased load, the turbine drops below the set point speed with the result, that the governor 50 effects clockwise movement of the arms 55, 61, and clockwise movement of the drive lever 70, effecting counter-clockwise movement of the link 77 about the pivot pin 85. This results in movement of the valve 80 to the left as shown in FIG. 4. The pivots 78, 81 are now positioned to the left of dash line 110. The inlet port 98 is now uncovered by the valve land 103 permitting the flow of fluid, such as oil under pressure, to the passage 96 for the introduction of oil pressure against the inner end of the piston 48, causing it to move to the left to shift the supply valve 30 farther toward open position for the admission of more steam to the turbine.

FIG. illustrates this movement of the piston rod with clockwise movement of the lever 87 about its fixed pivot 88, effecting movement of the link 77 about the pivot 78, now positioned by the governor 50, moving the valve 80 to the right to the normal or null position as shown in FIG. 5 after the speed change has been satisfied. In other words, the lever 87 and link 83 connected to the link 77 provides a follow-up mechanism to reposition the valve 80 when the turbine has returned to set point speed. This reduces the possibility of the piston 48 and valve 80 oscillating, or hunting, to provide greater stability in the speed control of the turbine.

The linkage assembly consists of components which may be economically formed from flat bar stock and are arranged for convenient assembly and maintenance resulting in a substantial cost reduction compared to the speed control arrangement now in use.

While for purposes of illustration, a preferred embodiment of this invention has been described. It will be apparent that the invention may be otherwise embodied within the scope of the following claims- I claim:

1. A speed control system for fluid operated turbines and the like comprising a fluid supply valve having a body formed with inlet and outlet openings, a seat structure intermediate said openings, a valve element movable into and out of engagement with said seat structure to control the flow of fluid from said inlet to said outlet, a frame attached to said valve body and being formed with a cylinder, a piston mounted for reciprocation in said cylinder, a piston rod extending from said piston to said valve element, a pilot control valve associated with said cylinder and being shiftable axially from normal position for the admission of fluid under pressure to said cylinder against alternate ends of said piston for movement of said valve element toward and tom said seat structure, a governor mechanism operatively connected to said turbine, a motion transconnecting said governor to said pilot control valve, said governor in conjunction with said motion transmitting means being operable to maintain said pilot control valve in normal position during operation of the turbine at the set point speed, said pilot control valve being operable in normal position to establish equal fluid pressure against the ends of said piston, said governor and said motion transmitting means being also operable to shift said pilot control valve from normal position in response to a change in the speed of said turbine from the set point speed thereof for actuation of said piston to effect movement of said valve element, said motion transmitting means including a rock shaft joumaled in said frame for oscillation by said governor mechanism and a linkage assembly connecting said rock shaft to said pilot control valve, said linkage assembly consisting of a first link pivotally connected at one end of said pilot control valve and extending radially therefrom, a connecting link pivotally connected at one end of said first link intermediate the ends thereof, a drive lever fixed to said rock shaft and being pivotally connected to the opposite end of said connecting link, a valve repositioning lever mounted at one end for oscillation about a fixed pivot and being pivotally connected intermediate its ends to one end of a repositioning link, said repositioning link being pivotally connected at its opposite end to the opposite end of said first link, the opposite end of said repositioning lever being pivotally connected to said piston rod.

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1. A speed control system for fluid operated turbines and the like comprising a fluid supply valve having a body formed with inlet and outlet openings, a seat structure intermediate said openings, a valve element movable into and out of engagement with said seat structure to control the flow of fluid from said inlet to said outlet, a frame attached to said valve body and being formed with a cylinder, a piston mounted for reciprocation in said cylinder, a piston rod extending from said piston to said valve element, a pilot control valve associated with said cylinder and being shiftable axially from normal position for the admission of fluid under pressure to said cylinder against alternate ends of said piston for movement of said valve element toward and from said seat structure, a governor mechanism operatively connected to said turbine, a motion transmitting means mounted exteriorly of said cylinder and connecting said governor to said pilot control valve, said governor in conjunction with said motion transmitting means being operable to maintain said pilot control valve in normal position during operation of the turbine at the set point speed, said pilot control valve being operable in normal position to establish equal fluid pressure against the ends of said piston, said governor and said motion transmitting means being also operable to shift said pilot control valve from normal position in response to a change in the speed of said turbine from the set point speed thereof for actuation of said piston to effect movement of said valve element, said motion transmitting means including a rock shaft journaled in said frame for oscillation by said governor mechanism and a linkage assembly connecting said rock shaft to said pilot control valve, said linkage assembly consisting of a first link pivotally connected at one end of said pilot control valve and extending radially therefrom, a connecting link pivotally connected at one end of said first link intermediate the ends thereof, a drive leVer fixed to said rock shaft and being pivotally connected to the opposite end of said connecting link, a valve repositioning lever mounted at one end for oscillation about a fixed pivot and being pivotally connected intermediate its ends to one end of a repositioning link, said repositioning link being pivotally connected at its opposite end to the opposite end of said first link, the opposite end of said repositioning lever being pivotally connected to said piston rod. 